Video Sequence Editor - How to make subtitles?
Since Blender 2.76 (or more detailled, since the Gooseberry Branch) there is a great new Text Effect Strip feature which will do the job for you! Mikeycal Meyers already made a great Tutorial on this topic.

Just Add Shift+A an E&#x332;ffect Strip... T&#x332;ext. You can animate it's opacity if needed and change it's size and position.